Pigments are versatile as colorants, and are widely used in the fields of coating materials, ink-jet inks, electrophotographic toners, color filters and so forth. When used in such fields, the pigments must finely be dispersed in mediums of various types in order to improve their coloring power and spectral characteristics such as transparency. However, such pigments having been made into fine particles commonly tend to cause the growth, transformation or the like of crystals because of their heat history and contact with solvents in the step of dispersion and subsequent steps for production to unwantedly cause problems such as a decrease in coloring power or transparency. Various pigment compositions and pigment dispersants for making up the compositions are proposed in order to remedy such problems. For example, a pigment composition is proposed in which an azo coloring matter different in type is added as a pigment dispersant to an azo pigment (see PTL 1). An example is also disclosed in which SOLSPERSE (registered trademark; available from Lubrizol Corporation) is used as a pigment dispersant (see PTL 2).
Meanwhile, as acetoacetanilide type disazo compounds, compounds various in chemical structure are proposed from old times as yellow or red colorants (see PTL 3).